In support of this central hypothesis, five supporting hypotheses are being tested...
Calhoun researchers are bringing back to life gauged watersheds built by the U.S. Forest Service over 50 year ago. Re-instrumentation of the catchments is necessary to forecast changes in hydrologic functioning of the Calhoun CZ, and thereby test the Ecohydrological Recovery Hypothesis.
Archived stream and rain data housed at Coweeta Hydrologic Laboratory contain a detailed record of hydrologic response of eroded watersheds from the 1940s to present. The ability to hindcast will contribute to testing the Ecohydrological Recovery, Erosion-induced Carbon Dynamics, and Dynamic Persistence of Alternative States Hypotheses.
In cooperation with Mr. Steve Stone, a local landowner, Dan Richter and Allan Bacon hired an engineering firm in 2010 to drill to a depth of nearly 70m.
Soil and unweathered granitic gneiss collected at regular intervals for comprehensive chemical analysis has established valuable measures of pedogenesis essential to testing the Biogeochemcial Decoupling Hypothesis.
The installation of an inverted tower at the Calhoun CZO will give reserachers access to deep soil, gas, and water samples. In conjunction with a eddy-covaraince flux tower to provide atmospheric data, direct observations from the uppermost to lowermost CZ will allow testing of the Decoupling Hypothesis, e.g. differences in carbon parameters between pristine hardwood and eroded plots.
Holcombe's Branch will be intensively sampled to quantify soucres and sinks of SOC. Using numerous approaches to the characterization of soil C, researchers will have a detailed history of carbon mobilization and stabilization in the watershed.
Quantifying the potential for Fe and Al-oxide rich subsoils to stabilize SOC relative to surface horizons is central to testing the Erosion-induced Carbon Dynamics Hypothesis.
The legacy of cotton cultivation fundamentally altered the landscape of the Southern Piedmont. While the Calhoun LTSE has traced biogeochemical changes that accompanied forest growth on old fields, socio-economic changes in the region have been remarkable as well.
The Gist family cemetery is a sober reminder of the area's plantation history. William Henry Gist was Governor of South Carolina from 1858-1860 and a strong advocate of secession. Today, the former Gist property, known as Rose Hill State Park, has reference hardwood stands and gullied old fields that are being studied as part of the Calhoun CZO.
Critical zone structure and function are being compared between remnant uncultivated hardwood forests, and directly adjacent old fields and pastures.
14 Nov 2018 - How critical zone science unearths secrets: The new cross-disciplinary field of study concerns itself with the living skin of the Earth.
10 May 2018 - The Discoveries section of the National Science Foundation's website on Critical Zone Observatories (CZOs).
01 May 2017 - Anna Wade (visiting from Duke University) and Jay Austin (based at the University of Georgia) are collaborating by using X-ray Diffraction (XRD) to...
27 Apr 2017 - The Forest History Society announces that Zachary Brecheisen is the 2017-18 recipient of the F. K. Weyerhaeuser Fellowship! The fellowship consists...
08 Dec 2016 - Bruno Latour, anthropologist and philosopher of science, gave a talk on Critical Zone science and the Anthropocene entitled "From the Anthropocene...
21 Nov 2016 - Four soil pits were installed in new Research Area 8 at the Calhoun CZO on 21-22 November 2016 for easy access for soil sampling down to 2 meters.
17 Oct 2016 - Eight soil pits were installed at the Calhoun CZO on 17-18 October 2016 for easy access for soil sampling down to 2 meters. Photo: Will Cook.
17 Aug 2016 - On August 17, 2016 a crew from Georgia Tech led by graduate student Yao Tang and professor Jingfeng Wang, with a little help from the folks at Duke,...
14 Jul 2016 - Another Calhoun CZO record - gas reservoirs installed at 8.5m depth! Jay Austin, Zach Brecheisen, and Dan Richter only stopped at 8.5m because they...
15 Nov 2015 - Get a sense of the people and the work. Several members of the Calhoun CZO are profiled here, including students and professors.
30 Oct 2015 - St. Clair et al. suggest tectonic stresses interact with topography to influence bedrock weathering.
09 Oct 2015 - About 60 Chinese and American critical zone scientists met in Guiyang, China for two days of discussions and presentations on the significance of...
19 Nov 2018 - The 2018 AGU Fall Meeting will be held December 10-14 in Washington, D.C.
06 Mar 2018 - A discussion is open for the manuscript, "Elevating the biogeosciences within environmental research networks".
01 Jan 2018 - New Opportunities for Critical Zone Science Following the June 2017 Arlington Meeting for Critical Zone Science (hosted by CZO), a white booklet...
05 Dec 2017 - Information on CZO award recipients, events, presentations, etc. at the 2017 AGU Fall Meeting.
30 Oct 2017 - Water Resources Research published a new special collection in September 2017 featuring concentration-discharge research from multiple CZOs.
Mercury sourcing and sequestration in weathering profiles at six Critical Zone Observatories. Richardson, Justin B., Arnulfo A. Aguirre, Heather L. Buss, A. Toby O'Geen, Xin Gu, Daniella M. Rempe, and Daniel deB. Richter (2018): Global Biogeochemical Cycles, doi: 10.1029/2018GB005974 Cross-CZO National
The formation of clay‐enriched horizons by lessivage. Calabrese, Salvatore, Daniel D. Richter, and Amilcare Porporato (2018): Geophysical Research Letters 45(15): 7588-7595
Loss of deep roots limits biogenic agents of soil development that are only partially restored by decades of forest regeneration. Billings, S.A., D. Hirmas, P.L. Sullivan, C.A. Lehmeier, S. Bagchi, K. Min, Z. Brecheisen, E. Hauser, R. Stair, R. Flournoy, D. deB. Richter (2018): Elementa Science of the Anthropocene 6(1): 34
Clays in the Critical Zone. Paul A. Schroeder (2018): Cambridge University Press Cross-CZO National
Ideas and perspectives: Strengthening the biogeosciences in environmental research networks. Richter, D.D., S.A. Billings, P.M. Groffman, E.F. Kelly, K.A. Lohse, W.H. McDowell, T.S. White, S. Anderson, D.D. Baldocchi, S. Banwart, S. Brantley, J.J. Braun, Z.S. Brecheisen, C.W. Cook, H.E. Hartnett, S.E. Hobbie, J. Gaillardet, E. Jobbagy, H.F. Jungkunst, C.E. Kazanski, J. Krishnaswamy, D. Markewitz, K. O’Neill, C.S. Riebe, P. Schroeder, C. Siebe, W.L. Silver, A. Thompson, A. Verhoef, G. Zhang (2018): Biogeosciences 15: 4815-4832 Cross-CZO National
Influences of Native American land use on the Colonial Euro-American settlement of the South Carolina Piedmont. Coughlan, Michael R., and Donald R. Nelson (2018): PLoS ONE 13(3): e0195036
Historical land use dynamics in the highly degraded landscape of the Calhoun Critical Zone Observatory. Coughlan, Michael R., Donald R. Nelson, Michael Lonneman, and Ashley E. Block (2017): Land 6(2), 32
Boom and bust carbon-nitrogen dynamics during reforestation. Parolari, A.J., M.L. Mobley, A.R. Bacon, G.G. Katul, D.deB. Richter, and A. Porporato (2017): Ecological Modelling 360: 108-119
Special issue of The Earth Scientist about the Critical Zone and the US NSF Critical Zone Observatory (CZO) program. CZO Education/Outreach team (2016): The Earth Scientist, Volume XXXII, Issue 3, Fall 2016 Cross-CZO National
Geophysical imaging reveals topographic stress control of bedrock weathering. St. Clair, J., S. Moon, W. S. Holbrook, J. T. Perron, C. S. Riebe, S. J. Martel, B. Carr, C. Harman, K. Singha, D. deB. Richter (2015): Science, 30 October 2015, Vol. 350, no. 6260, pp. 534-538 Cross-CZO National
Micro-topographic roughness analysis (MTRA) highlights minimally eroded terrain in a landscape severely impacted by historic agriculture. Brecheisen, Zachary S., Charles W. Cook, Paul R. Heine, and Daniel deB. Richter (2019): Remote Sensing of Environment 222: 78-89
Carbon and oxygen isotope composition in soil carbon dioxide within deep Ultisols at the Calhoun CZO, South Carolina, USA. Cherkinsky A., Brecheisen Z , Richter D. (2018): Radiocarbon
Unified representation of the C3, C4, and CAM photosynthetic pathways with the Photo3 model. Hartzell, Samantha, Mark S. Bartlett, and Amilcare Porporato (2018): Ecological Modelling 384: 173-187
Similarities in the evolution of plants and cars. Hartzell, Samantha, Mark Bartlett, Jun Yin, Amilcare Porporato (2018): PLoS ONE 13(6): e0198044
State dependent jump processes: Ito–Stratonovich interpretations, potential, and transient solutions. Bartlett, M.S., and A. Porporato (2018): arXiv:1807.01848
Evaluating the effect of nutrient redistribution by animals on the phosphorus cycle of lowland Amazonia. Buendía, Corina, Axel Kleidon, Stefano Manzoni, Björn Reu, and Amilcare Porporato (2018): Biogeosciences 15: 279-295
Ecohydrological model for the quantification of ecosystem services provided by urban street trees. Revelli, Roberto, and Amilcare Porporato (2018): Urban Ecosystems 21(3): 489-504